The 2020+ optional 4 piston fixed calipers have already started replacing the NNBS brake upgrade, and fits on NBS, NNBS, and K2XX. Its been reported that some 17s are fitting and some aren't. (There may even be a style of 18s that don't work). Lets start a list of which ones do and which ones don't.

Helpful information will include:
OE Type OR Brand and model
Wheel size, and offset if aftermarket, (some wheels come in multiple offsets - E.T. on the wheel is offset).
Picture of face (for easy identification), and inside to show clearance, or actual measurements would be helpful.
Did I miss anything?

 

About time someone started this, I have tested 3 wheels so far.

1: OEM NNBS LTZ20s. Fit with a 1/4" spacer or serious caliper front face hump grinding.

2: Method race wheels roost 17x8.5 4.75back spacing. Fit without a spacer but the barrel clearance is very close.

3: OEM NBS Denali 17s. Do not fit ends of caliper contact inner barrel of the wheel.

Once I finish the swap I'll test a few other wheels I have laying around.

 

Hoping some more people can add to this. I would really like to know if the 18" black high country wheels and the 18" titan 5 spokes will fit.

 

I've seen some people use the 17" wheels from the GMT800 trucks, one guy ground the outside of the caliper down and used a wheel spacer, but it fit. I dont remember the specifics on it because i have 20" SS reps so I didnt feel l needed to remember it.

 

Yeah, I don't usually bump things like this, but I think this is a thread people need to see first, then remember it when they do it, so they know there is somewhere they can help others out. I will add to this thread, with something I haven't seen on any of the other threads about this brake upgrade.

Here is a 7:38 video where they list the parts, part numbers, and WHAT I HAVEN'T SEEN ON ANY OF THE OTHER THREADS ABOUT THIS, is the size of the spacers needed to line them up correctly,
0.15" thick, 1.11" OD, 0.54" ID,


EVENTUALLY... SOMEBODY is going to make a bunch of these spacers, and do a good old fashioned group buy on em. (Hopefully it won't take people prematurely wearing out one side of the rotor and pads, and dramatically reducing the life of these before this becomes the norm). I know we have some machinists in here. If you do, you can put me on the list.

It would also help to know if people are using washer's, spacers, or modifying anything to make them fit. A ID measurement of the wheel's barrel would help as well.

 

Heck, just in case. Maybe we can motivate someone to make these spacers. Depends on price but,

Interested in buying a set of spacers made at the right size specifically for this:
1. adriver

 

I can confirm that K2XX 20" High Country wheels fit with TONS of clearance.

Also - used these washers to get the spacing correct and they worked great.

https://www.ebay.com/itm/15113766883...4AAOSwtpZYSIBe

 

As for the spacers in your link, the specs on those are:
1/2" AN960 Thin Flat Washer 18-8 Stainless Steel Made in USA Military spec. ID: 1/2" (.50) OD: 7/8" (.875) Thick: 1/32 (.0312)

Don't take this personal, but you weren't 100% clear on how you measured it. I'm just going to say I haven't measured it myself. Up to this point, people are mounting them even without spacers. They will work/fit, but it's going to work better and last longer if the measurement is spot on. For the sake of everyone else who may read this thread, I'm just adding this "disclaimer".

If these worked for you, then at the least we know that ID .50 -.54" works. Somebody could easily measure the mounting bolt and see the minimum ID required.
The O.D of 7/8" - 1.11 (/ 1 1/8"(1.125)) will work. I have not mounted so I don't know what might interfere with the OD.
The concern on the ones you posted is the thickness. It would take 5 of those to equal the thickness compared to the measurement posted in the video, and that's the most important measurement out of the three. The other two need to just be good enough, but the thickness is going to center the caliper over the rotor. The washers you posted are 1/32 thick. The video says .15" thick, which is 5/32 thick (.156").


So I started searching to see if any standard washer sizes come close (to the measurements in the video) and found this:
2014-AMPG-Washer-CatPgs.indd

Here you see 7/16 bolt size is almost spot on. These are 1/32" smaller on the ID from what we know works.




So, I can't yet guarantee that ID will work without increasing the ID by no more than 1/16", but the closest off the shelf washer I could find would be Z9184-BEV-SS

ZORO SELECT Z9184-BEV-SS 7/16" x 1" OD Plain Finish 18-8 Stainless Steel | eBay

GRAINGER APPROVED Stainless Steel Beveled Washer, Plain Fastener Finish, Fits Bolt Sizes 7/16 in - 1JYB4|Z9184-BEV-SS - Grainger




(Different, but close, MIGHT be a second place option)

 

Regarding the washers....umm...I go to Ace Hardware and stand there with a caliper at the 1/2" washer bin finding any between .100-.125". Match up 4 and move on....

 

Yeah that's one not as accurate option. Do you want to keep it going or can we agree that if the caliper is not centered on the rotor; you WILL either have a longer pedal travel to engage, OR (on light braking) you will wear away one side of the pads and rotor quicker, wearing them out faster overall?

For some people, time, gas money, you just spent the same for $15 washers in those links as you would spending $1 in the store.